With an AC generator of this type incorporated into a vehicle, there has been a need for a higher generator output power to meet an increase of electric loads in the vehicle. A stator winding that generates a generator output power therefore tends to be disposed within a slot of the stator core by enhancing space efficiency.
A stator in the rotating electric machine is disclosed, for example, in JP-UM-A-2-103754 (Prior Art 1). According to the stator in the rotating electric machine disclosed in Prior Art 1, plural slots are formed on the inner periphery of the stator core, and a stator winding is disposed within each slot. Two insulation structures are adopted for the stator winding.
One insulation structure is an insulation coating formed on each slot peripheral wall. The slot peripheral wall has a slot bottom wall and a pair of slot side walls opposing to each other, and the slot bottom wall and the pair of slot side walls are formed on the stator core. The insulation coating made of an electrical insulation material is formed on the slot bottom wall and the pair of slot side walls, and the insulation coating electrically isolates the stator winding disposed within the slot from the stator core forming the slot peripheral wall.
The other insulation structure is an electrical insulation member called a wedge for closing a slot opening that opens in the inner peripheral surface of the stator core. The electrical insulation member prevents intrusive substances, such as water, saline water, slurry, and dust, having entered into the rotating electric machine from entering into the slot through the slot opening, and thereby prevents the electric insulation of the stator winding within the slot from being damaged by the intrusive substances. The electrical insulation member is inserted into the slot so as not to fall off with the use of a pair of hanging portions formed on the slot side walls, and closes the slot opening in such a manner that an internal space for disposing the stator winding in the slot will not be reduced excessively.
A stator in the rotating electric machine is also disclosed in JP-A-2000-14068 (Prior Art 2). Prior Art 2 discloses a stator in which an insulation sheet is disposed between the outer periphery of the stator winding disposed within the slot and the stator core forming the slot peripheral wall. The insulation sheet is formed to enclose the outer periphery of the stator winding disposed within the slot.    Patent Document 1: JP-UM-A-2-103754    Patent Document 2: JP-A-2000-14068